Question: The country of Sylvania has decided to reduce the number of its illiterate citizens by $\dfrac35$ each year. This year there are $9000$ illiterate people in the country. Write a function that gives the number of illiterate people in Sylvania, $P(t)$, $t$ years from today. $P(t)=$
Explanation: If the number of illiterate people decreases by $\dfrac{3}{5}$ of its size each year, that means $\dfrac{2}{5}$ of that number remains each year. So each year, the number of illiterate people is multiplied by a factor of $\dfrac{2}{5}$ (or $0.4$ ). If we start with the initial number, $9000$, and keep multiplying by $\dfrac{2}{5}$, this function gives us the number of illiterate people in Sylvania $t$ years from today: $P(t)=9000\left(\dfrac{2}{5}\right)^t$